1. Field of the Invention
This invention relates to devices for quantifying chemical exposure and/or content. More particularly, it relates to devices for quantifying ethylene oxide and methods for their use.
2. Background
Ethylene oxide (EO) is widely used as a chemical reactant and as a sterilizing agent whose toxic efficacy is dose-dependent. Accordingly, it is of interest to have available methods or devices to measure the degree of sterilizing dose which has been applied to an article to be sterilized. For quality assurance purposes, it is desired to have a method or device that can express ethylene oxide exposure in industry accepted numerical terms of concentration and time. Since EO is toxic, it is also of interest to have available a method for determining EO residual levels in plastics after sterilization.
The device described herein is characterized as being a true dosimeter for ethylene oxide exposure rather than merely an indicator of exposure.
In the context of medical, industrial, and forensic science, the most crucial decisions are made daily on the basis of measurement (analysis of quantity, mass, extent, or degree in terms of a standard unit of measure), whereas mere indication (demonstration of the probable presence or nature of) can only be used as corroborative evidence.
In the context of measurement science, a "true dosimeter" is a device which measures the integral over time of chemical concentration (i.e. time-average concentration), usually specified in the International System (SI) of Units as: [(Mass).times.(Time).div.(Volume)], e.g. g-hour/l.
The present devices are dosimeters that measure a true ethylene oxide dose (concentration-time integral), and can for that matter, report the dose as an analytically measured result in unambiguous units referenced to a primary standard (e.g., g-hour/l referenced to the International System (SI) of Units).